1. Field of the Invention
The invention relates generally to digital/video projectors of the type connectable to a computer, usually a laptop, and are used in making presentations where slides are stored on a computer, such as with Microsoft PowerPoint presentations. More specifically, the invention relates to a system for enabling better cool-down of the light source and electronic componentry in such a projector to enable longer service life.
2. Related Art
It is well known that projectors, and particularly projector lamps, become very hot in operation, due to the heat generated by the lamps during operation. Moreover, where the light output is being directed through a printed circuit board with a digital light processor or liquid crystal display for projection, this electronic componentry can become hot as well because the intense light source placed proximate thereto. It has long been known that longer life in such devices can be achieved by providing for improved controlled cool-down after operation, and that such cool-down time can be enhanced by running a cooling fan after the light source has been switched off. Otherwise, when the cooling fan is turned off simultaneously with the light source, residual heat is not quickly dissipated and the temperature can briefly rise to a level that can damage the lamp and shorten its useful service life compared to properly using the cooling fan until the lamp is sufficiently cooled. This can also shorten the service life of the electronic componentry for essentially the same reasons.
Recognizing this fact, projection equipment has been configured to operate the cooling fan after the light source is turned off until the lamp is sufficiently cool. This cool-down has typically been done by providing a cool-down power switch setting manually selected by an operator, which turns on the fan while the light is off. This cool-down function has also been implemented by providing a timer or thermostat and configuring the projector to run the cooling fan automatically for a period of time after turning off the light source. In the latter case the timer or the thermostat provides a cut off signal when the device is below a temperature threshold in the case of the thermostat, or the fan has run long enough to provide the requisite cooling as predetermined and preprogrammed in a control system in the case of the timer.
However, in the case of digital/video projectors used in presentations at meetings, it is often the case that the projector is unplugged to allow the next presenter to use a power outlet for similar equipment. As such, if the cool-down functionality is provided for, the operator often voluntarily or involuntarily overrides the cool-down step in favor of disconnecting the projector from power and moving it or packing it away without allowing for the recommended or desired cool-down time. Often, users are simply in a hurry after using the projector and they unplug the device, or simply turn it off and leave the room, etc. and do not allow the cool-down for this reason of perceived need for haste at the expense of the cool-down of the device. As a consequence typical bulb service life, which would be expected to be about 2000 hours if the cool-down procedures recommended by the projector manufacturer were followed, can be reduced to approximately half that expected, or about 1000 hours, further depending on other factors such as rough handling, vibration, etc, to which the device is exposed. Moreover, the service life of the other electronic componentry may be shortened also due to extreme overheating when the cool-down step is not performed.
Accordingly, there is a need for a system and method of ensuring that a projection lamp and other electronic componentry utilized in a projection system have sufficient time to cool down properly regardless of whether the projection system is plugged in or turned off.
It has been recognized that it would be beneficial to provide for a post light source shut off cool down period where the cooling fan runs even if the device is unplugged after shutting it off. Accordingly, a projector is disclosed that comprises a light source cooling fan and power supply, and further includes a portable power supply, such as a battery or solar cell power source, such that the projector is configured to run the cooling fan from the portable power supply automatically for a sufficient time enough after shutoff to cool down the light source, regardless of the actions of the operator.